Why did the US support the Shah Mohammed Reza Pahlavi of Iran?

Mohamad reza shah pahlavi aka aryamehr was the consistently the most pro US leader in middle east during his 37 reign. Iran's economy and military and anything in between was some how modeled Americans.He was the first Muslim leader to establish realtionship with Israel and urged president saddat of Egypt to make peace with the Jewish state. He aligned Iran's interest with that of USA in the region and was instrumental in keeping soviet union's ambitions in check by signing many military agreements with US. Ironically in his last interview with David forest in Panama , the shah blamed the US for his ouster. The shah had grown very powerfull and was begining to move away from US camp, this led to falling in favor with US and his fall from power. He did what he could to keep Iran growing and being in peace with its neighbors in that very volitale region.Oil, plain and simple. U.S. and Britains have been tangled up in the oil business in the Mideast for many years. Brits started all this. Churchill was key, initially. Later, Truman refused to involve the U.S. but, later, Eisenhower accept Brit BS that they would turn Commies if U.S. didn't help. U.S. got tangled up in Iran and then with Israel and now Iraq and Afghanistan.